Sill pans are well-known for constituting flashing for a wide variety of apertures or openings in various structures, especially those for doors and windows in buildings. As flashing, sill pans provide the final barrier between exterior water and the vulnerable interiors of a structure. As such, sill pans are vital for maintaining the integrity of a structure against undesirable moisture migration, and other external factors that can degrade an unprotected building interior. Accordingly, the optimum arrangement to protect an interior from moisture migration and the like is to provide sill pans manufactured specifically for a particular size and configuration of opening.
However, there are so many variations in the aperture sizes for windows and doors that manufacturing specific sill pans for each becomes prohibitively expensive. This is due to the fact that most sill pans are formed by various plastic manufacturing methods, such as injection molding or extrusion. The processes requires specific tools made for each size and configuration of the final product. Since each tooling is extremely expensive, the manufacture of whole sill plates for every type and size of window and door opening is prohibitively expensive.
The industry response has been adjustable sill pans. This has been accomplished most often by the use of arrangements in which one part of the sill pan slides under an adjacent part. This approach has had a number of draw-backs. Firstly, to accommodate a wide range of sizes, extremely large sill pans with substantial overlaps have had to be used. This is wasteful of material, even if it is capable of accommodating a wide range of apertures.
Unfortunately, the overlapping of the two parts of the sill pan creates gaps through which moisture might migrate and enter vulnerable parts of the structure. Further, substantial overlaps lead to awkward installation. Also, to properly interlock the overlapping sill pan parts, complex interlocking structures have to be manufactured as part of the multiple overlapping sill pans. This adds a considerable amount of expense to the manufacture to what should be a relatively simple structure that must be used in many openings (both door and window) of a structure. Likewise, complex interlocking structures lead to difficulty during installation when workmen might not be familiar with a particular sill pan interlocking arrangement.
Accordingly, there is a need in the building industry for an adjustable sill pan system that is simple to install, inexpensive, and efficient against the entry of water or other environmental effects. Further, such a system would have to be easily adjustable to fit a wide range of different entryway and window apertures.